1. Field of the Invention
The present invention relates to a method for recycling a recording material comprising at least a surface portion which swells in contact with water, and bears thereon deposited images by the electrophotographic method, the thermal transfer method or the ink-jet method using a hot-melt ink; and an apparatus for recycling the above-mentioned image-deposited recording material.
The method and apparatus for recycling the image-deposited recording material according to the present invention can be applied to a media board capable of automatically erasing the images formed thereon.
2. Discussion of Background
With the recent spread of printers and copying machines employing various kinds of image forming processes such as an electrophotographic method, thermal transfer method or ink-jet method using a hot-melt ink, a large quantity of papers have been used and consumed. This has caused the problems of the environmental disruption of the earth due to deforestation because papers generally used as recording materials contain pulp as a raw material. In addition, with the increase of consumption of the papers, the problem of waste treatment has become serious.
A transparent sheet is also used as the recording material for an overhead projector (OHP). Such a transparent sheet employs as a base material a plastic film such as a polyester film. Most of the raw materials for use in such a plastic film are made of petroleum. It is therefore desired to make efficient use of resources with the drain of oil resources taken into consideration. In addition, most plastic films have no biodegradability, so that after these plastic films are discarded, they will float on the ocean as dust. It follows as a consequence that the environmental disruption is induced.
Conventionally, in order to solve the above problems, used papers or films are collected and subjected to beating or melting again to recycle such recording materials. However, the energy cannot be efficiently used in this recycling method, with the result that the cost may become higher as compared with the case where papers and films are made of new raw materials, or the quality of the papers and films obtained by the above-mentioned recycling method is lowered.
There is proposed a method for recycling papers and films on which images are deposited by the electrophotographic process, as disclosed in Japanese Laid-Open Patent Applications 1-101576 and 1-101577. According to this method, a toner-image-bearing copy paper or film is immersed into a solvent in which toner images formed on the copy paper or film are soluble, and is then subjected to an ultrasonic wave treatment, thereby removing toner images form the copy paper or film. Since the solvents commonly used in this method, such as acetone/trichlene and methyl butyl ketone, are ignitable and toxic, this method is not good from the viewpoints of safety and hygiene. Further, this recycling method is achieved by dissolving the toner images in the solvent, so that the solvent is contaminated with the toner in a short period of time. Therefore, a large quantity of solvent is required. In addition, there is the problem that the toner component once dissolved in the solvent is again deposited to the surface of the paper to induce the toner deposition. It is very difficult to solve such problems.
There is proposed a method for recycling a recording material made of a non-absorbent material such as plastics, metals, papers into which liquids hardly penetrate, and ceramics, as disclosed in Japanese Laid-Open Patent Application 1-297294. According to this recycling method, a thermofusible releasing member is overlaid on the toner-image-bearing recording material with the application of heat thereto, whereby toner images are peeled from the recording material.
Furthermore, there is proposed a sheet-shaped image-bearing member for supporting images thereon as disclosed in Japanese Laid-Open Patent Application 4-67043. This image-bearing member can be reused by making one side of the sheet releasable, and this kind of sheet is distinguished from a plain copy paper by marking the sheet.
In those recycling methods, however, not only plain copy papers cannot be used as the recording materials, but also it is necessary to select a recording material with poor adhesion to the toner images or to subject a recording material to releasing treatment in order to facilitate the removal of the toner images from the recording material. In such recycling methods, easy peeling of the images from the recording material means insufficient fixing performance of the recorded images. Therefore, when the images deposited on the recording material are rubbed by the clothes and the fingers, the images easily fall off the recording material and the clothes and fingers are stained with toner.
To solve the aforementioned problems, the inventors of the present invention have proposed a method for recycling an image-bearing recording material, at least part of the recording material comprising a paper layer which comprised cellulose fibers, as disclosed in Japanese Laid-Open Patent Application 5-202557. This recycling method comprises the steps of impregnating the image-bearing recording material with a water-containing liquid to weaken the adhesion between the paper layer and a thermally flexible ink deposited on the paper layer of the recording material; and bringing an image release member into pressure contact with the image-bearing surface of the recording material; and peeling the ink from the paper layer. This recycling method has the advantages that images formed on a plain copy paper for general use can also be removed therefrom, and there is no problem in terms of safety.
In Japanese Laid-Open Patent Application 5-96619, the inventors of the present invention have proposed an apparatus for recycling the image-bearing recording material to embody the recycling method as disclosed in Japanese Laid-Open Patent Application 5-202557. It is found that this recycling method can be applied to not only the above-mentioned recording material mainly comprising the cellulose fibers, but also a recording material comprising at least a surface portion capable of swelling in contact with water and bearing deposited images.
The conventional recycling method as disclosed in Japanese Laid-Open Patent Application 5-202557, however, has the drawbacks. Namely, when the recording material bears a lot of solid images thereon, it is difficult to separate the image release member from the image-bearing recording material. In such a case, a large quantity of water-containing liquid (hereinafter referred as an image removal promoting liquid) must be applied to the recording material to perfectly remove the images from the recording material. Further, the temperature must be considerably increased when the images are transferred from the recording material to the image release member. In addition, the kind of recording material and the kind of material for use in the image are relatively limited to carry out this recycling method.
The drawbacks of the conventional recycling method will now be explained in detail by referring in FIG. 1.
According to the recycling method of Japanese Laid-Open Patent Application 5-202557, the image removal promoting liquid is applied to the image-bearing recording material to decrease the adhesion between the image and the recording material, and the image release member to which the image can adhere more easily than to the recording material is brought into contact with the image-bearing surface of the recording material with the application of pressure and/or heat thereto, thereby transferring the ink image from the recording material to the image release member.
FIG. 1 is a schematic view which shows one embodiment of an apparatus for achieving the above-mentioned conventional recycling method. An image-bearing recording material 15 placed on a paper-feed tray 1 is sent to a guide plate 3 by a paper-feed roller 2 and led to an image release roller 5 by a transporting roller 4, with the image-deposited surface of the recording material 15 being directed to the guide plate 3. In this structure, an image removal promoting liquid 7 is supplied to the surface of the image release roller 5 by means of a liquid supply roller 6. Therefore, the image removal promoting liquid 7 is applied to the image-bearing recording material 15 as the recording material 15 is transported along the image release roller 5, so that the image-bearing surface of the recording material 15 is impregnated with the image removal promoting liquid 7. After the image-bearing recording material 15 is caused to pass through a nip between the image release roller 5 and a heat application roller 8 with the application of heat and pressure to the recording material 15, the recording material 15 is separated from the image release roller 5 by means of a separating claw 9.
The components for constituting the image (hereinafter referred to as an image-constituting material) transferred to the image release roller 5 are cleaned by a cleaning member 10, and then the image removal promoting liquid 7 is again applied to the surface of the image release roller 5 for the next recycling process.
The recording material 15 free from images separated from the image release roller 5 is lead to a drying belt 12 by a first transporting roller 11 to dry the recording material 15. Then, the recording material 15 is transported to a paper receiving tray 13 by a second transporting roller 11. The recording material 15 discharged to the paper receiving tray 13 is cleared of the images, so that it is ready to be reused.
One of the drawbacks in such an embodiment of the conventional recycling method is that when a plain paper is used as the recording material 15, it is necessary to apply the image removal promoting liquid 7 to the paper to such a degree that the paper is substantially saturated with the liquid 7 in order to perfectly peel the images from the paper. When a large amount of image removal promoting liquid is applied to the recording material, the energy required to dry the recording material is increased. It is therefore impossible to carry out the recycling process as high speed. A plain paper swells in contact with the water component contained in the image removal promoting liquid, so that the stiffness of paper is decreased, with the result that it is made difficult to transport the wet paper in the recycling apparatus as shown in FIG. 1, and the size of paper finally becomes different from the original size. In addition, when a large quantity of image removal promoting liquid must be applied, the size of container for storing the image removal promoting liquid therein necessarily increases, thereby making the size of the recycling apparatus bigger. Furthermore, when the image-free recording material is dried, a large amount of water is evaporated, so that there are the problems that the humidity abnormally increases in the recycling apparatus, and the water vapor is condensed in the recycling apparatus to induce the trouble of electrical circuits.
The other problems of the above-mentioned conventional recycling method is that is may be difficult to separate the recording material from the image release member after the images are attached and transferred to the image release member by the application of heat and pressure thereto. The occurrence of this problem depends upon the kind of material for use in the recording material, the king of image-constituting material, and the kind of image pattern formed on the recording material. One of the reasons for this problem is that the adhesion of the image to the recording material cannot sufficiently be reduced even though the image removal promoting liquid is applied to the image-deposited surface of the recording material. When the area of image portions is relatively small in the entire recording material, the recording material can readily be separated from the image release member with no difficulty. In the case where the image pattern formed on the recording material includes many solid images, the separation of the recording material from the image release member becomes difficult because the contact are of the recording material and the image release member is large.